Characteristics of Dry Matter Accumulation and Translocation During the Wheat Genetic Improvement and Their Relationship to Grain Yield

【Objective】To verify the characteristics of dry matter accumulation,translocation and their relationships to grain yield during wheat genetic improvement will facilitate development of new cultivars for stable and high yielding wheat production.【Method】 Thirty two wheat cultivars bred or widely planted in China from 1950 to 2005 were grown in field experiments from 2007 to 2009.Dry matter accumulation and growth rate at different stages,leaf area index(LAI) and net photosynthetic rate(Pn) were measured,and dry matter translocation and their relationship to grain yield formation were analyzed.【Result】 Grain yield and harvest index increased linearly with the progress of wheat cultivar evolution,whereas the biomass of the cultivars from 1950 to 1960 reduced and thereafter maintained stable.Leaf area,LAI and flag leaf Pn at anthesis increased linearly with the cultivars evolution,supplying the sources of dry matter and energy for yield formation after anthesis.Genetic improvement increased the dry matter accumulation and growth rate at the growth stages of emergence to jointing and anthesis to maturity whereas reduced the contribution of post-anthesis accumulated dry matter to grains(CPA).Grain yield was significantly and positively associated with the contribution of pre-anthesis translocation to grains(CPT),dry matter accumulation and growth rate from emergence to jointing and anthesis to maturity,whereas significantly and negatively correlated with CPA,dry matter accumulation and growth rate from jointing to anthesis.【Conclusion】Dry matter production capacity and production efficiency were improved during wheat cultivar evolution,yet dry matter accumulation at different growth stages were coordinated and the contribution of pre-anthesis and post-anthesis accumulation to grains became more balance.Improving the pre-jointing vegetative growth post-anthesis accumulation and CPT are important physiological basis for wheat grain yield enhancement,which will be a key improvement target for high yield wheat breeding in the future.